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Sub-wavelength broadband metamaterial absorber for low-frequency noise control

A technology of low-frequency noise and metamaterials, applied in the direction of sound-generating devices and instruments, to achieve good suppression and broadband absorption efficiency

Inactive Publication Date: 2020-03-20
NANJING UNIV +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0005] The technical problem to be solved by the present invention is that, aiming at the deficiency that the existing sub-wavelength low-frequency sound absorbers only work at a single frequency, a near-perfect sub-wavelength wide-band design utilizing a metamaterial resonator coupled with a porous sound-absorbing sponge is proposed ( >98%) absorber, which can efficiently suppress low-frequency noise in a wide frequency band

Method used

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  • Sub-wavelength broadband metamaterial absorber for low-frequency noise control
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  • Sub-wavelength broadband metamaterial absorber for low-frequency noise control

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Experimental program
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Effect test

Embodiment 1

[0026] Use 3D printing technology to print and process a metamaterial resonator integrating 6 Helmholtz resonators. The parameters are shown in Table 1. The height of the metamaterial resonator is 40 mm, and a cylindrical ring with a thickness of 4 mm is cut with a sponge cutting tool. The metamaterial resonator is embedded in the sponge, so far a complete absorber cell is processed, and the integrated metamaterial resonator can provide 6 resonances with wavelengths much larger than its size. Such as image 3 As shown, the cells are arranged according to the period d=160mm and placed at s=15mm in front of the hard boundary 5. The hard boundary 5 only requires that the impedance of the boundary is far greater than the acoustic impedance of the air. In practical applications, it can be realized by building walls . The absorption curve obtained in this way is as follows Figure 5 As shown, the frequency range of the sound absorption coefficient greater than 98% is 231Hz to 326H...

Embodiment 2

[0028] In order to further reduce the frequency of the sound wave without changing the external dimensions of the metamaterial resonator, this embodiment uses 3D printing technology to print and process a metamaterial resonator integrating four Helmholtz resonators. The parameters are shown in Table 1 , the height of the metamaterial resonator is 40mm, use a sponge cutting tool to cut a cylindrical ring with a thickness of 4mm, and embed the metamaterial resonator into the sponge, so far a complete absorber unit is processed and formed. Similarly, the cells are arranged in a period d=150mm and placed at s=13mm in front of the hard border 5 . The absorption curve obtained under this installation method is as follows Image 6 As shown, the sound absorption coefficient is greater than 98%, the frequency range is 188Hz to 238Hz, and the corresponding wavelength is 28.5R o to 22.5R o .

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Abstract

The invention discloses a sub-wavelength broadband metamaterial absorber for low-frequency noise control. The absorber comprises a plurality of absorber cells. Each sound absorber cell comprises a metamaterial resonator and an acoustic sound absorption sponge thin layer. The metamaterial resonators are integrated with a plurality of Helmholtz resonators. The Helmholtz resonators are fan-shaped. The outer circumferential parts of the fan-shaped resonators are arranged to be labyrinth channels. The circle center parts of the fan-shaped resonators are arranged to be solid bodies, and fan-shaped annular cavities are formed between the labyrinth channels and the solid bodies. The acoustic sound absorption sponge thin layer is coated outside the metamaterial resonator. The absorber can absorb broadband sound energy with the wavelength far larger than the size of the absorber in an approximately perfect mode, and has a good inhibiting effect on broadband low-frequency noise.

Description

technical field [0001] The invention belongs to the technical field of acoustic noise reduction, and relates to a broadband absorber for low-frequency sound waves, in particular to a sub-wavelength broadband near-perfect absorber based on the coupling of a labyrinth metamaterial resonator and an acoustic porous material. Background technique [0002] Noise pollution has become the fifth largest pollution source in the 21st century, and noise control has increasingly become an important topic in the field of acoustics. The absorption of sound energy is a very important method of suppressing noise. Traditional acoustic materials, such as porous sound-absorbing sponge, mainly rely on the air friction loss between the gaps, and because the dissipation coefficient follows the linear response theory, the porous material absorbs high-frequency sound waves better, but absorbs low-frequency sound waves very weakly. Therefore, appreciable absorption of low-frequency sound waves requir...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G10K11/162
CPCG10K11/162
Inventor 龙厚友冯奇万庆冕程营陶建成刘晓峻邵雪飞
Owner NANJING UNIV
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